Trace elemental behavior in the solar nebula: Synchrotron X-ray fluorescence analyses of CM and CR chondritic iron sulfides and associated metal

We have performed a coordinated focused ion beam (FIB)-scanning and transmission electron microscopy (SEM, TEM)-electron probe microanalysis (EMPA)-synchrotron X-ray fluorescence (SXRF) microprobe study to determine phase-specific microstructural characteristics and high-resolution in situ trace element concentrations of primary pyrrhotite, pentlandite, and associated metal grains from chondrules in CM2 and CR2 carbonaceous chondrites. This work is the first of its kind to link trace element chemical and microstructural observations in chondritic sulfides in an attempt to determine formation mechanisms and conditions of primary sulfides in these meteorite groups. SXRF and TEM analyses were performed on a small number of FIB sections which act as representative samples of primary sulfides and associated metal present in pyrrhotite-pentlandite intergrowth (PPI) grains and sulfide-rimmed metal (SRM) grains.